gha: codeql: minor touch-ups and fixes

- remove trailing whitespace
- pin to a versioned ubuntu version
- adjust timeout to be more within expected duration
- remove redundant git checkout, which is no longer needed

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

.github/workflows/codeql.yml

@@ -33,8 +33,8 @@ on:
 
 jobs:
   codeql:
-    runs-on: 'ubuntu-latest'
-    timeout-minutes: 360
+    runs-on: ubuntu-24.04
+    timeout-minutes: 10
     env:
       DISABLE_WARN_OUTSIDE_CONTAINER: '1'
     permissions:
@@ -48,11 +48,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 2
-      -
-        name: Checkout HEAD on PR
-        if: ${{ github.event_name == 'pull_request' }}
-        run: |
-          git checkout HEAD^2
       # CodeQL 2.16.4's auto-build added support for multi-module repositories,
       # and is trying to be smart by searching for modules in every directory,
       # including vendor directories. If no module is found, it's creating one